A California man suspected of building a bomb and arrested after an FBI manhunt may also face a felony charge connected to a lethal toxin.

A prosecutor told a federal judge Monday that high-ranking officials at the U.S. Department of Justice are deciding whether to add the toxin charge to the two felony counts Ryan Chamberlain already faces.

Chamberlain is charged with possessing explosive material and a handgun missing its serial number.

Chamberlain was arrested in early June after a three-day manhunt that authorities said was prompted by the discovery of bomb-making materials and evidence of illegal toxins in his apartment in San Francisco.

Chamberlain apparently came to the attention of the FBI as it investigated and monitored an online marketplace where people allegedly bought and sold guns, bombs, drugs, chemicals and counterfeit goods.